Thanks to a changed energy awareness of the population and supported by state funding initiatives, the use of renewable energy sources has gained increasing economic importance—this applies in particular for the field of photovoltaics, the conversion of sun light into electric power. In many places—not only in Germany—highly productive, state of the art factories were built in which today photovoltaics modules (PV modules) are manufactured as a mass produced article with to the most efficient methods in order to be shipped to all parts of Europe and the world.
In the standard version, PV modules consist of a single-pane safety glass on the front side, two fused layers of transparent laminating film between which the photovoltaics cells, in most cases made of silicon, and an electrical conductor system are embedded, and a special plastic film which seals the back side in a vapor diffusion tight manner. This is also referred to as glass/plastic module. In contrast, the so-called glass/glass modules are provided on the back side with a glass pane.
On the one hand, PV modules can be equipped with a frame made of a metal section, for example, a drawn aluminum section, which frame, for example, has a depth of 42 mm. On the other hand, frameless PV modules—in the version as glass/plastic module and also as glass/glass module—are also manufactured and shipped.
The size of PV standard modules is in most cases in the range between 0.8 m2 and 1.6 m2. The weight of framed modules lies mostly in the range between 14 and 28 kg and for unframed modules, depending on the size, between 5 and 20 kg, wherein glass/glass modules can be 60% heavier than glass/plastic modules.
It has already been recognized in the past that the considerations with respect to innovative rationalization must not be limited to manufacturing-related criteria, but must also include the areas storage, packaging, shipping and transport security.
For the transport to the customer, the PV modules were usually individually packaged in cardboard and stacked horizontally on top of one another on wooden pallets. To secure a stack of individual packages against slipping, the stack was connected to the pallet by means of tensioning straps.
However, this commonly used method of transport packaging of PV modules involved serious disadvantages. This includes an enormous amount of necessary packaging material, in particular cardboard packaging, and a significant amount of work for packing as well as unpacking of the individually cartoned PV modules at the end user. In addition, there was the thankless task to collect considerable amounts of cardboard boxes at the installation site and, if required, to shred and recycle the cardboard. Moreover, with this method, the PV modules could be stacked only up to a limited stacking height because the weight of the stacked modules adds up and is transferred onto the modules at the very bottom. In addition to this static load there is also a dynamic load during the transport, for example, by abrupt dropping with the forklift, acceleration forces, deceleration forces and centrifugal forces during truck transport and particularly by vibrations when driving over speed bumps and potholes. This can easily result in damage to the module or modules at the very bottom if the stack is too high.
Thus, packaged PV modules could be transported very rarely in stacking heights of more than 1 m, wherein, due to the risk of overloading the modules at the bottom, it was also not possible to stack two loaded pallets on top of each other so that often only a part of the available loading height of the cargo area of a truck could be utilized.
Another essential disadvantage of packaging PV modules with cardboard is that cardboard boxes are sensitive to moisture and can not be exposed to rain because they can not provide any stability or protection anymore in the wet state.
Due to these disadvantages, other solutions for stacking, storing and transporting PV modules have been developed.
For example, from the patent Abstracts of Japan Bd. 2000, No. 06, Sep. 22, 2000 and JP 2000 079961 A, Mar. 21, 2000, a modular plug-in system for safely storing and transporting of horizontally stacked photovoltaics modules (PV modules) is known. The system is configured as frame construction which is formed by four vertically running columns and horizontal struts connecting the latter. A plurality of frame units of the frame construction can be stacked on top of one another and can be connected by means of a plug-in connection. Each frame unit has four column sections and struts connecting the same. For plugging column sections together which are arranged on top of one another, the respective column section has a pin at the top and a recess at the bottom. The photovoltaic modules are stored in two of the four horizontal struts, namely in two struts arranged parallel to one another of the respective frame unit. For this, the two struts receive displacement parts on which the module rests. The respective column section of the column is configured as flat rod with formed ends.
Furthermore, from the European patent specification EP 1617485 B1 of the applicant, a modular plug-in system for safely storing and transporting horizontally stacked photovoltaic modules (PV modules) is known. This system is formed exclusively from individual, vertically arranged load-bearing columns which each consist of molding members which are arranged on top of one another and form the column when plugged together. On the side oriented towards the photovoltaic module, each of these molding members is equipped with a load-bearing carrier profile as support device for the photovoltaic module and has on the upper side and lower side, respectively, one or more pins or a key, and on the lower side and upper side, respectively, one or more open cavities for fittingly receiving the pin(s) or a groove for receiving the key.
However, in case of frameless PV modules, stacking horizontally aligned modules on top of one another is only suitable to a limited extent if at all. Specifically for relatively large-sized frameless PV modules, due to the effect of the high static and dynamic loads, there is a high risk of breakage. Therefore, for storing and transporting purposes, frameless PV modules are preferably stacked side by side with vertical alignment of the modules, in the same manner as this is common practice also for flat glasses.
For stacking flat glasses side by side, stationary as well as mobile shelf constructions are used, similar to the one illustrated in FIG. 17.
In principle, such shelf construction could also be used for storing and transporting frameless PV modules, but these shelf constructions could receive only a few modules. Moreover, it would not be possible to lean several PV modules against one another because normally each PV module has a projecting junction box on its backside. It is also to be considered that an empty shelf is still very bulky and heavy and thus requires a considerable effort during transportation.
Therefore it was or still is common practice to package also vertically aligned frameless PV modules in cardboard boxes for the storage and in particular for the transport. For this purpose, specially adapted cardboard boxes are available, for example, similar to the one shown in a simplified manner in FIG. 18. According to FIG. 18, such a cardboard box comprises a lower part for receiving a plurality of vertically aligned frameless PV modules, and an upper part which serves as cover. In order that the vertically aligned frameless PV modules do not fall over or collide with each other, at least the bottom of the lower part and the cover of the upper part have comb-like inserts, for example made of corrugated board, on the inner side facing the PV modules, wherein between each two tooth-like projections of a comb-like insert, a PV module is positioned. The tooth-like projections are wide enough that a contact of two PV modules, even considering the junction boxes projecting on the back side, is excluded. For a simpler handling, the whole cardboard box is placed on a transport pallet.
The company Eckpack-Service GmbH & Co. KG (http://www.eckpack.de) suggests to use a modular plug-in system, similar to the one of the European Patent Specification EP 1617485 B1 of the applicant, not only for stacking horizontally aligned PB modules on top of one another, but that with said system also stacks of PV modules can be generated which are vertically aligned and arranged side by side, as it is exemplary shown in the FIGS. 19, 20 and 21. For this, the individual PV modules are first provided at each of their four corners with one molding member of said modular plug-in system and are then stacked in horizontal alignment on top of one another before finally the whole stack is rotated so that the PV modules in the stack are now vertically aligned.
However, it is of disadvantage that a molding member of this modular plug-in system is adapted to framed PV modules and thus is configured to encompass the frame with its spring arm and to lock into place behind the frame (cf. FIGS. 19 and 21). However, such a molding member would have no possibility to engage on a frameless PV module so that this modular plug-in system can not be used for stacking vertically aligned frameless PV modules side by side.
Moreover, a disadvantage of the solution proposed by Eckpack is that a stack of PV modules, which are vertically aligned and arranged side by side, formed with said plug-in system is relatively instable if the stack is not held together by additional tensioning straps or bands (cf. FIG. 16) placed around it and not secured in particular along the stacking direction against slipping or falling apart.
Another disadvantage of the solution proposed by Eckpack with respect to frameless PV modules is that the corners and edges of each vertically aligned PV module within the stack, in particular the lower corner and edge areas on which the respective module rests and on which therefore the whole weight of the module acts, would be insufficiently protected against potential damage. This could be damages only on the surface such as, for example, scratches which occur due to vibrations during the transport if the corner and edge areas of the frameless PV modules enclosed by the molding members rub against the molding members. However, there would also be the risk that due to shocks during the transport, broken particles chip off or splinter off.
Therefore, as a result of the considerations explained herein, an object to be solved is to provide a system for safely storing and transporting frameless PV modules whilst avoiding at least one of the described disadvantages.